From: Rob Herring (Arm) Date: Tue, 17 Dec 2024 18:11:42 +0000 (-0600) Subject: mfd: syscon: Allow syscon nodes without a "syscon" compatible X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ba5095ebbc7a;p=users%2Fjedix%2Flinux-maple.git mfd: syscon: Allow syscon nodes without a "syscon" compatible of_syscon_register_regmap() was added for nodes which need a custom regmap setup. It's not really correct for those nodes to claim they are compatible with "syscon" as the default handling likely doesn't work in those cases. If device_node_get_regmap() happens to be called first, then of_syscon_register() will be called and an incorrect regmap will be created (barring some other error). That may lead to unknown results in the worst case. In the best case, of_syscon_register_regmap() will fail with -EEXIST. This problem remains unless these cases drop "syscon" (an ABI issue) or we exclude them using their specific compatible. ATM, there is only one user: "google,gs101-pmu" There are also cases of adding "syscon" compatible to existing nodes after the fact in order to register the syscon. That presents a potential DT ABI problem. Instead, if there's a kernel change needing a syscon for a node, then it should be possible to allow the kernel to register a syscon without a DT change. That's only possible by using of_syscon_register_regmap() currently, but in the future we may want to support a match list for cases which don't need a custom regmap. With this change, the lookup functions will succeed for any node registered by of_syscon_register_regmap() regardless of whether the node compatible contains "syscon". Signed-off-by: Rob Herring (Arm) Tested-by: Will McVicker Reviewed-by: Pankaj Dubey Reviewed-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20241217-syscon-fixes-v2-3-4f56d750541d@kernel.org Signed-off-by: Lee Jones --- diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index bfb1f69fcff1d..226915ca3c93d 100644 --- a/drivers/mfd/syscon.c +++ b/drivers/mfd/syscon.c @@ -171,9 +171,12 @@ static struct regmap *device_node_get_regmap(struct device_node *np, break; } - if (!syscon) - syscon = of_syscon_register(np, check_res); - + if (!syscon) { + if (of_device_is_compatible(np, "syscon")) + syscon = of_syscon_register(np, check_res); + else + syscon = ERR_PTR(-EINVAL); + } mutex_unlock(&syscon_list_lock); if (IS_ERR(syscon)) @@ -238,9 +241,6 @@ EXPORT_SYMBOL_GPL(device_node_to_regmap); struct regmap *syscon_node_to_regmap(struct device_node *np) { - if (!of_device_is_compatible(np, "syscon")) - return ERR_PTR(-EINVAL); - return device_node_get_regmap(np, true); } EXPORT_SYMBOL_GPL(syscon_node_to_regmap);